class Yukicoder
  def initialize
    n = gets.chomp.to_i
    a = gets.chomp.split(' ').map(&:to_i)
    hash = Hash.new(0)

    a.each do |num|
      hash[num] += 1
    end

    puts hash.count{|k,v| v==1}
  end
end

Yukicoder.new